Conventionally in an image forming optical system of an inverted microscope, there are an optical axis of an objective lens (hereafter referred to as an “objective optical axis”), and an optical axis constituting a part of an image forming optical path at a lens barrel side (hereafter referred to as a “lens barrel optical axis”). These objective optical axis and lens barrel optical axis are positioned at the center of the microscope unit (hereafter referred to as the “main body portion”), and are often disposed in parallel at the front and back when the side of an ocular is at the front (e.g. see Patent Document 1).
There is a type of inverted microscope which has a light source for illumination, so that the illumination light is guided from the light source to the illumination optical system, and illuminates a sample through an objective lens. Light from the sample is condensed by the object lens and is guided to the ocular via the image forming optical system. The user can observe the image of the sample through the occular (e.g. see Patent Document 2).
An aperture is disposed in the middle of the illumination optical system, and the user adjusts the illumination state by controlling the aperture so that the sample is appropriately illuminated.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2003-75726
[Patent Document 2] Japanese Patent Application Laid-Open No. 2005-234279
However according to the above mentioned conventional configuration of the inverted microscope, the objective optical axis is inevitably disposed in the back of the main body portion. The stop, which is in the middle of the illumination optical system, is also disposed behind the lens barrel support.
In such a conventional inverted microscope, visibility, controllability and operability for the user are not very good. For example, it is difficult to see what kind of objective lens is currently installed. In other words, visibility of the objective lens is poor.
Control of a revolver when magnification is changed, that is switching control of the objective lens, for example, is also difficult. Operability to replace samples or to change position of a sample is also not very good. In this way, if the optical path of the illumination optical system is positioned in the depth direction from the top view, the position of an element to control the stop is distant from the user, which makes operability poor when the user controls the stop while observing a sample through the ocular.